Create install_julia.sh

[grantmcdermott]

Would fix #128

I expect you'll want to change certain things about the script, but I just tested locally and it seems to work fine for me. Happy to continue the discussion here.

[eitsupi]

Checking other scripts, I think there is room for modification in the way the PATH is set.

rocker-versioned2/scripts/install_pyenv.sh

Lines 22 to 24 in 3b41d37

	# pipenv requires ~/.local/bin to be on the path...
	echo "PATH=/opt/pyenv/bin:~/.local/bin:$PATH" >> ${R_HOME}/etc/Renviron
	echo "PATH=/opt/pyenv/bin:~/.local/bin:$PATH" >> /etc/bash.bashrc

How to set environment variables is currently being discussed in #151 (comment), but the above description seems to be the standard at this time.

I am not an expert in these scripts or PATH settings, so if this comment is incorrect, please feel free to ignore it.

[eitsupi]

I think we may extract the latest stable version of Julia from the json file which Julia versions' information is recorded.

If we are allowed to use the jsonlite and the purrr packages and pipe operator in R, we can get 1.6.1 like this.

library(jsonlite)
library(purrr)
library(dplyr)

js <- jsonlite::read_json("https://julialang-s3.julialang.org/bin/versions.json")

versions <- names(js)

is_stable <- purrr::map(js, ~ .x$stable == TRUE) %>%
  purrr::as_vector()

versions[is_stable] %>%
  sort(decreasing = T) %>%
  {.[1]}

I don't know how to do the same thing without installing any packages or tools...

[eitsupi]

When we install JuliaCall, the yaml package is also installed, and we can use yaml::read_yaml to read json file, so it looks like we can get the latest Julia version without any additional packages.

js <- yaml::read_yaml("https://julialang-s3.julialang.org/bin/versions.json")

versions <- js |>
  names()

is_stable <- Map(function(x) x$stable, js) |>
  unlist()

versions[is_stable] |>
  sort(decreasing = TRUE) |>
  (function(x) x[1])()

in bash

$ Rscript -e "
js <- yaml::read_yaml('https://julialang-s3.julialang.org/bin/versions.json')

versions <- js |> \
  names()

is_stable <- Map(function(x) x\$stable, js) |> \
  unlist()

versions[is_stable] |> \
  sort(decreasing = TRUE) |> \
  (function(x) x[1])() |> \
  cat()" | cat
1.6.1

[grantmcdermott]

Close in favour of #269.